Driven by the recent advances in the technologies of digital storage and audio compression, the problem of managing very big collections of audio files becomes predominant. For instance, the current generation of MP3 players contains a 10 GB hard disk drive which enables users to store e.g. more than 300 hours of MP3PRO music, meaning more than 4.000 titles.
Reliable tools are required to make those collections accessible to the users.
The classical way of indexing audio files is based on textual meta-information like title, artist, album or genre, like e.g. ID3 tags for MP3 audio files.
There are some drawbacks with this kind of organization:                1. The metadata are textual and not audio, and therefore cannot give a precise representation of an audio content, like a representative extract of the content can do.        2. Organization sorted by genre or by artist allows users to locate a particular piece of music. This presupposes that users have well-defined goals, knowing exactly what they want to hear. The users searching strategy must be goal-driven and deterministic.        3. There are a lot of genres: for instance, the music archive mp3.com currently lists its titles under 180 different sub-genres, organized in 16 main genres. It is difficult for a user to navigate in such organization.        4. Genres are sometimes subjective because they are established a priori and not deduced from the content itself. Sometimes they are difficult to interpret.        5. A classification by genres is not able to satisfy very simple user needs like for instance “This piece of music is relaxing me. I would like to hear more like this”.        
The present invention is directed to overcoming these drawbacks.